[WIP] port profile page to backbone.js

this will port the javascript on profile pages
`/people/[guid]` and
`/u/[username]`
to use a backbone view.

Not finished, will create a backbone model in order to handle rendering more gracefully,
also, the persons stream doesn't show at this stage.
```ruby
return :not_sharing unless contact

[:mutual, :sharing, :receiving].find {|status|
  contact.public_send("#{status}?")
}